A computer network is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information. Communication protocols define the rules and data formats for exchanging information in a computer network. A cache is a mechanism that can store and serve data. For example, a web cache may store web content from servers so that clients can access the content from the cache more quickly than from the servers.
Web proxies are a common component in many computer network environments. They are used for a variety of purposes including saving bandwidth and providing a controlled path out to the Internet from a local network. Web proxies store content from the Internet in a cache so that if access to that same content is later sought by a computer being serviced by the proxy, the web proxy can fetch the requested content from the local cache instead of retrieving another copy from the Internet.